In vehicles provided with internal combustion engines, such as automobiles and the like, it has been proposed in recent years that the operation of the engine be automatically stopped when engine operation is not required, such as when, for example, the vehicle has no possibility of moving, to improve the fuel economy of the engine.
While the internal combustion engine of the vehicle is automatically stopped, various types of auxiliary devices, such as a water pump, a compressor, and an oil pump, are driven by a motor rather than being driven by the internal combustion engine. When auxiliary devices are driven by a motor while the internal combustion engine is automatically stopped in this way, it is desirable that the drive force of the motor be transmitted only to the auxiliary device and not transmitted to the engine. To achieve this goal, Japanese Laid-Open Patent Publication No. 10-339185, for example, proposes blocking power transmission between a motor and an internal combustion engine by means of a clutch when driving auxiliary devices with a motor.
When there is a demand to move the vehicle while the engine is automatically stopped, forced rotation of the internal combustion engine is required in order to start the engine. From the perspective of reducing the number of components of the vehicle, the forced rotation of the internal combustion engine for the purpose of starting the engine is also performed by the motor in the above publication. That is, when a start command is issued to the automatically stopped internal combustion engine, the motor is driven in a state in which the clutch connects the motor and the internal combustion engine to forcibly rotate the internal combustion engine.
Since it is desirable to lighten the weight of the vehicle in order to improve the fuel economy of the internal combustion engine, the aforesaid motor has been progressively made more compact, or with lower capacity. A decrease in the output of the motor is an unavoidable result of making the motor smaller, and if the motor is made too small, the motor will not be capable of forcibly rotating the internal combustion engine adequately to start the engine. Therefore, the compactness of the motor is limited by the need for the motor to provide sufficient forcible rotation of the internal combustion engine and properly start the engine.
In view of this fact, an object of the present invention is to provide a device for controlled starting of an internal combustion engine capable of allowing maximum compactness of the motor while providing sufficient forcible rotation of the internal combustion engine which is adequate to start the engine.